The present invention relates to a process for temperature control, and in particular to a process for the temperature control of a drying apparatus in which the raw material which has been charged into the entrance thereof is dried so that the moisture rate of the raw material is kept constant and is discharged from the exit thereof.
For example, when cut tobacco leaves are dried, it is desirable that the finished product possess a predetermined moisture.
The period of time after the raw material cut tobacco leaves is charged into the drying apparatus until the amount of the raw material held at each part of the drying apparatus is stabilized to a substantially constant state, that is, the flow rate of the raw material at the exit of the drying apparatus is stabilized is referred to rise-up time or unsteady time, which differs from the subsequent period referred to as stable time or steady time.
If a similer temperature control is carried out during both periods, drying would be excessive at rise-up time and final product would not possess the desired moisture. For example if the period of the rise-up time is 10 to 15 minutes in a drying apparatus into which raw material is supplied at a flow rate of 6000 kg/h, there is a possibility of production of 50 to 100 kg of undesired product.